Localization bugs are often classified into these symptom buckets:
Build/BVT (1) breaks
This kind of bug would make it impossible to produce a localized build, or would make a build completely unusable. These bugs are increasingly rare; when they...

This has been bugging me for a good while:
It was decided that the name of the component "Ultimate Extras" should not be translated in Swedish Windows Vista. So why on earth would it be translated in the display name for an update? Answer: no reason...